This invention relates to water resistant wood composition boards and methods of making the boards by coating or impregnating the panels with a solvent soluble, further curable, partial condensation product of a methyltrialkoxy silane or a phenyl trialkoxy silane or mixtures thereof or ladder-type organosilsesquioxane polymers as described in the Bagley et al. U.S. Pat. No. 4,835,057.
Wood-based composite panels such as particle boards are used as paneling and siding in indoor and outdoor construction.
Low cost construction products such as inside paneling and outside siding are currently manufactured by printing and/or embossing an inexpensive sheet, or piece, of fiberboard (hardboard). The low-cost fiberboard, however, is sensitive to moisture and water reaching fiberboard through the exposed surface is the current quality problem which limits the useful product lifetime. Current practice is to coat an exposed surface with a thin organic plastic coating. This coating can be either a thermoset or uv-cure, but thermosets are generally used to reduce the cost (thermoset resins are cheaper). Much of the paneling is used in showers and tub areas and, of course, outside siding is exposed to the weather. Current practice provides marginally adequate protection against water so product lifetime is marginally adequate.
The present invention is directed to increasing the product lifetime of wood composition board construction products (e.g., paneling and siding) by reducing the permeability of water through use of a siloxane coating or impregnation. The best candidate is an organosilsesquioxane (ladder siloxane) having methyl (CH3) pendant groups (prepared preferably from methyl triethoxysilane), as this material has the highest volume fraction of SiO1.5. However, ladder siloxanes with other pendant groups (e.g., phenyl) or mixtures (e.g., methyl and phenyl) are also candidates. In addition, admixture of linear siloxanes and/or linear organic polymers can be added to the ladder siloxane (if they are all soluble in the same organic solvent) so as to achieve a particular property (e.g., coating flexibility). However, such additions will increase the permeability of water, and in the limit of having 100% organic polymer that is generally current practice. The ladder siloxanes can be either thermosets or uv-cured, but the thermosets are less expensive and completely compatible with the current product manufacturing process. The resins are solid at room temperature and soluble in organic solvents to a controllable viscosity. Because it is the wood composition board that needs protection, the siloxane can be applied in a number of places in the manufacturing sequence. As examples: the resin could be a component in the manufacture of the board (binding the wood fibers together); it could be impregnated in the board after its manufacture; it could be a coating on the board prior to design printing; it could be a replacement for the final organic coating now used, or it could be a final coating on top of the current practice. One added benefit of having it as a final coating is that the high SiO1.5 content of the ladder siloxanes gives them better abrasion resistance than organic coatingsxe2x80x94an advantage in cleaning installed paneling.
It is desired to have wood composition boards that have increased resistance to permeation by water and resultant deterioration.
It is an object of the present invention to provide a method of treating wood composition boards to reduce the penetration of water therethrough by coating or impregnating the panels with a solvent soluble, further curable organosilsesquioxane polymer of the formula shown in an idealized structure: 
wherein R and Rxe2x80x2 may be the same and are selected from the group consisting of:
a) aliphatic hydrocarbons of 1-4 carbon atoms;
b) a phenyl radical;
c) a phenyl radical substituted with hydroxy or halogen groups; and
d) halogen groups, provided that R and Rxe2x80x2 are not both halogens;
w, x, y, and z are functional groups selected from the group consisting of alkoxy groups of 1-4 carbon atoms, halogen atoms, hydroxyl groups and silanol groups, and n is an integer ranging from 10-200.
It is an object of the present invention to provide a water-resistant wood composition board treated by coating or impregnating a hydrolysis and a partial condensation reaction product of a solvent soluble organopolysiloxane which is the reaction product of methyl triethoxysiloxane and water or a mixture of a methyl triethoxy silane and phenyl triethoxy silane and water.
It is an object of the present invention to provide wood composition boards that are used in panel construction or as siding, the panels being coated or immersed in a solvent soluble, further curable, hydrolysis and partial condensation product that is an organosilsesquioxane polymer including an organopolysiloxane resin made from methyl triethoxysilane or a mixture of phenyl triethoxysilane and methyl triethoxysilane.
It is an object of the present invention to provide a method of treating wood composition boards to reduce the penetration of water therethrough by coating or impregnating the boards with a solvent soluble, further curable organopolysiloxane resin that is a hydrolysis and partial condensation product of water and (A) methyl trialkoxy silane, or (B) a mixture of (A) and a phenyl trialkoxy silane.
These and other objects of the invention will be apparent from the specification that follows and the appended claims.
The invention provides a method of treating wood composition boards to reduce the penetration of water therethrough by coating or impregnating the panels with a solvent soluble, further curable organosilsesquioxane polymer of the formula: 
wherein R and Rxe2x80x2 may be the same and are selected from the group consisting of:
a) aliphatic hydrocarbons of 1-4 carbon atoms;
b) a phenyl radical;
c) a phenyl radical substituted with hydroxy or halogen groups; and
d) halogen groups, provided that R and Rxe2x80x2 are not both halogens;
w, x, y, and z are functional groups selected from the group consisting of alkoxy groups of 1-4 carbon atoms, halogen atoms, hydroxyl groups and silanol groups, and n is an integer ranging from 10-200.
The present invention provides a method of treating wood composition boards to reduce the penetration of water therethrough by coating or impregnating the panels with a solvent soluble, further curable organopolysiloxane resin that is a hydrolysis and partial condensation product of water and (A) methyl trialkoxy silane, or (B) a mixture of (A) and a phenyl trialkoxy silane.